I appreciate some of this is will be early beta stuff but these are a couple of things I’ve noticed over the day. Apologies if ready reported.
In Help>Elements Manual it’s pointing to the wrong URL (https://help.realmacsoftware.com whereas the correct URL is Welcome to Elements | RapidWeaver Elements Docs)
The help and info contextual menus in the node browser aren’t working. I assume these would go directly to help for the selected component?
Undo doesn’t work after pasting into a heading or paragraph component
You can’t copy/paste and maintain the copied items style
Command-D always duplicates a page, even if you have something else selected eg. a component. This can be alarming as you’re working on a full page, attempt to duplicate a component with command-D and suddenly there’s a blank page in front of you.
There seems to be a bug with text styles. I’ve selected a heading component and changed the font family to Serif. It displays correctly on screen and in a Safari preview but it won’t save. When reopening the document the custom font has reverted to the original theme font. UPDATE: If you choose another custom font as the style it saves OK, it’s only if you choose a default font that it fails.
On a more positive note:
Globals are cool 
It would be great to have some sort of Globals library which could work across documents.
I love the text style over-ride being right there to change width and weight
Even though I’ve had my frustrations I’m already enjoying it more than Rapidweaver with a bunch of stacks. It’s visually so much better.
A nice addition would be the ability to eyedropper a style and apply it to other text.
A standard colour picker for Themes>Colour would be nice, I found creating a new colour set a bit odd.
Stability wise it’s been fantastic for an early beta. A couple of crashes when undoing but otherwise very impressive. The fact most chatter on the beta feedback forum is for changes to features or GUI rather than bugs is a testament to how solid a base you have - well done.